Lighthouse
Google's open-source tool for auditing performance, accessibility, SEO, and best practices. Built into Chrome DevTools.
Overview
Lighthouse is an open-source, automated tool for improving the quality of web pages. Created by Google, it audits web pages across five categories: Performance, Accessibility, Best Practices, SEO, and Progressive Web App (PWA). Lighthouse is built into Chrome DevTools, available as a browser extension, and can be run from the command line or in CI/CD pipelines.
Lighthouse is unique among testing tools because it covers multiple quality dimensions in a single audit. It is often the first quality tool added to a web project because it requires zero setup and provides immediate, actionable feedback.
What it's used for
Lighthouse is essential for:
- Performance auditing: Measure Core Web Vitals (LCP, FID, CLS) and identify performance bottlenecks.
- Accessibility quick checks: Catch common accessibility issues automatically.
- SEO validation: Ensure pages are discoverable by search engines.
- CI/CD quality gates: Block deployments that degrade performance or accessibility scores.
Pros & Cons
Pros
- Free and built into Chrome — zero setup
- Covers performance, accessibility, SEO, and best practices
- Actionable recommendations with estimated savings
- Can run in CI via Lighthouse CI
- Backed by Google — scores influence search rankings
Cons
- Limited to Chrome rendering engine
- Accessibility checks are basic compared to Axe
- Performance scores can vary between runs
- Mobile simulation is not a substitute for real device testing
- SEO checks are rudimentary compared to dedicated tools
Platforms & Integrations
Lighthouse runs in Chrome, as a CLI tool (Node.js), or in CI via Lighthouse CI. It audits any publicly accessible web page.
Pricing
| Tier | Cost | Includes |
|---|---|---|
| Open Source | Free | All audits, CLI, CI integration, browser extension |
NZ Context
Lighthouse is ubiquitous in NZ web development. Every NZ frontend developer and tester should know how to run a Lighthouse audit. Google's PageSpeed Insights (which uses Lighthouse) is frequently referenced in NZ digital marketing and SEO contexts. For NZ government websites, Lighthouse accessibility scores are sometimes used as a proxy for WCAG compliance, though dedicated tools like Axe are preferred for thorough testing.
Alternatives
- WebPageTest — More detailed performance testing with real device and connection profiles.
- Axe — More comprehensive accessibility testing.
- GTmetrix — User-friendly performance reporting with historical tracking.